Upgrade rust/crates/tokio to 1.12.0

Test: make
Change-Id: I4b0bd405c0b615f886e5a6606e0bf7c0ac7c6699

1 files changed, 7 insertions, 6 deletions

diff --git a/src/io/util/fill_buf.rs b/src/io/util/fill_buf.rs
index 98ae2ea..3655c01 100644
--- a/src/io/util/fill_buf.rs
+++ b/src/io/util/fill_buf.rs
@@ -34,15 +34,16 @@ impl<'a, R: AsyncBufRead + ?Sized + Unpin> Future for FillBuf<'a, R> {
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
         let me = self.project();
 
-        // Due to a limitation in the borrow-checker, we cannot return the value
-        // directly on Ready. Once Rust starts using the polonius borrow checker,
-        // this can be simplified.
         let reader = me.reader.take().expect("Polled after completion.");
         match Pin::new(&mut *reader).poll_fill_buf(cx) {
-            Poll::Ready(_) => match Pin::new(reader).poll_fill_buf(cx) {
-                Poll::Ready(slice) => Poll::Ready(slice),
-                Poll::Pending => panic!("poll_fill_buf returned Pending while having data"),
+            Poll::Ready(Ok(slice)) => unsafe {
+                // Safety: This is necessary only due to a limitation in the
+                // borrow checker. Once Rust starts using the polonius borrow
+                // checker, this can be simplified.
+                let slice = std::mem::transmute::<&[u8], &'a [u8]>(slice);
+                Poll::Ready(Ok(slice))
             },
+            Poll::Ready(Err(err)) => Poll::Ready(Err(err)),
             Poll::Pending => {
                 *me.reader = Some(reader);
                 Poll::Pending